Hydrocarbon conversion



March 23, 1965 H. w. PARKER 3,175,019

HYDROCARBON CONVERSION Filed Nov. 30, 1959 ATTORNEY United States PatentO 3,175,019 HYDRGCARBQN CQNVERSIN Harry W. Parker, Bartlesville, Ghia.,assigner to Phillips Petroleum Company, a corporation or Delaware FiledNov. 30, 1959, Ser. No. 856,108 2 Claims. (Ci. 26th- 683) This inventionrelates to the pyrolysis of hydrocarbons and to the conversion of saidhydrocarbons into hydrocarbons having a lower hydrogen content. In oneaspect, this invention relates to a hydrocarbon converison process inwhich at least a portion of the heat required for the reaction issupplied by the oxidation of solid carbonaceous material in the presenceof the hydrocarbon being converted. In another aspect, the inventionrelates to passing a mixture of a hydrocarbon and an oxygencontainingcomponent through a bed of solid carbonaceous material under conditionssuch that oxidation of the carbonaceous material takes place, therebysupplying a-t least a portion of heat necessary for the conversion ofhydrocarbon. In another aspect, the invention relates to a hydrocrabonconversion process in Which at least a portion of the heat required forthe process is supplied by oxidizing a solid carbonaceous material, saidsolid carbonaceous material being maintained in a iiuidized bed incontact with said hydrocarbon. In another aspect, the invention relatesto a hydrocarbon conversion process in which at least a portion of theheat required for the process is supplied by oxidizing a solidcarbonaceous material in the presence of said hydrocarbon andtransferring heat from a quench zone downstream of a reaction zone to apreheat zone upstream of said reaction zone. In another aspect, theinvention relates to a hydrocarbon conversion process in which at leasta portion of the heat of the reaction is supplied by oxidizing a solidcarbonaceous material in the presence of the hydrocarbon in which thedirection of ilow through the reaction zone is reversed periodically toutilize heat extracted from the hydrocarbon leaving the reaction zone topre-heat the hydrocarbon flowing to the reaction zone. In anotheraspect, the invention relates to reactor apparatus suited for use inendothermic reactions.

In the pyrolysis of hydrocarbons it is well known and has been customaryto oxidize a portion of the feed stream while crackling the remainder.Thus, the oxidized portion of the feed supplies the heat of crackingnecessary for converting the remainder of the feed. This process hasbeen used for the conversion of parainic hydrocarbons to oleiins. Forexample, such a process has been used for the preparation of ethylenefrom various gaseous feeds including methane, propane, ethane, andbutane. In the prior art processes, oxygen, air or oxygen enriched airhave been used as oxidants; co-current, counter-current, venturi andtangential mixing have been utilized to bring about the partialoxidation of the hydrocarbon feed; regenerative furnaces have beenadapted to utilize the heat more eiiciently in preheating the feed andquenching the reaction products. Such processes, however, have not beenacceptable in certain areas where the feed material is in relativelyshort supply or must be imported. These processes have beendisadvantageous both for economic reasons and by reason of governmentrestrictions in some countries requiring a strict accounting of heatcontent of materials entering into a reaction process.

It is an object of the present invention to reduce the amount ofhydrocarbon feed which must be oxidized to supply the heat forconverting said hydrocarbon. Another object of this invention is tosupply at least a portion of the heat necessary for hydrocarbonconversion process by oxidizing a solid carbonaceous material in thepresence of the hydrocarbon feed converted. Another lil Patented Mar.23, 1965 object of this invention is to provide a hydrocarbon conversionprocess which results in the off-gas after separation of the producthaving a relatively high content of combustible material, thus making itsuitable for use as a commercial heating gas. It is another object ofthis invention to provide a process in which an endothermic conversionis balanced by exothermic oxidation of a material other than thereactant. Another object is to provide improved apparatus suitable foruse in endothermic processes.

Other aspects, objects, and the several advantages of the invention areapparent from a study of the disclosure, the drawing, and the appendedclaims.

Thus, my invention provides an improved process for the conversion ofhydrocarbons in which heat is supplied to the process by oxidizing asolid carbonaceous material in the presence of the hydrocarbon beingconverted. This invention also provides a hydrocarbon conversion processcomprising passing the hydrocarbon through a reaction zone containingsolid carbonaceous material while simultaneously oxidizing thecarbonaceous material. In one embodiment, the carbonaceous material ispresent in the form of a fluidized bed of solid particles.

My invention includes a hydrocarbon conversion process in which thehydrocarbon passes through adjacent reheat, reaction, and quench zones,and a portion of the heat supplied by oxidizing the solid carbonaceousmaterial in the reaction is removed in the quench zone and transferredtherefrom to `the preheat zone. My invention further provides ahydrocarbon conversion process in which the hydrocarbon being convertedpasses through successive preheat, reaction, and quench zones, heat issupplied to the hydrocarbon in the reaction zone by the oxidation ofsolid carbonaceous material therein and heat is transferred from thequench zone to the preheat zone by cycling solid particles between thequench and preheat zones. My invention also provides a hydrocarbonconverison process comprising periodically reversing the direction of owof the hydrocarbon feed through a pair of regeneration zones, separatedby a reaction zone in which heat is supplied to the hydrocarbon byoxidation of solid carbonaceous material.

My invention also provides apparatus suited for use in an endothermicprocess, the apparatus comprising a preheat chamber, a reaction chamberdownstream of said preheat chamber, and a quench chamber downstream ofsaid reaction chamber, a bed of solid carbonaceous material in saidreaction chamber, and means to supply heat from asid quench chamber tosaid preheat chamber. In one embodiment, the means to supply heatcomprises means to transfer solid particles cyclically between saidquench and preheat chambers. My invention also provides apparatuscomprising a pair of regeneration chambers separated by a reactionchamber, solid carbonaceous material in said reaction chamber, and meansto oxidize said material and means to reverse the direction of flow ofthe hydrocarbon through said pair of regeneration chambers and saidreaction chamber.

When the heat of an endotherermic hydrocarbon converison is supplied,according to my invention, by a carbon rich fuel such as coke, coal,charcoal, or other solid carbonaceous material, in a partial oxygenationreaction, the gaseous products contain relatively high proportions ofhydrogen, carbon monoxide and methane, thus providing an oli-gas, afterseparation of the conversion products, high in combustible material andbeing suitable for use as a commercial heating gas. For example,ethylene and propylene can consequently be maunfactured from propane incountries where the latter material must be imported, thus making ituneconomical to carry out the reaction by oxidizing a portion of thefeed, and wherein government restrictions require an accountingaart/1,019

of heat content into a process and practically full conversion of theheat content to useful energy. Countries in which such restrictions areimposed and which also have adequate supplies of solid carbonaceousmaterials suitable for the practice of the invention include England,France, Germany, and Italy.

Hydrocarbons in general are -adaptable for use as the feed in thepractice -of the present invention. However, although high aromaticfeedstocks cannot be entirely omitted Ias possible feed constituents,hydrocarbon materials having predominantly paraflinic characteristicsgenerally provide more desirable feedstocks. A further desirablecharacteristic is a relatively low viscosity. Thus, satisfactoryfeedstocks include normally gaseous hydrocarbons, naphthas boiling inthe range of about 100 to 400 F., Ykerosenes boiling in the vrange `ofabout 300 to 500 F., and light gas oils boiling in the range of 400 to500 F. Such materials asv diesel fuels and the various fuel oils can beused provided they have a viscosity and a boiling range suitable for theprocess.

It is Well known that olefins can be prepared from the feedstocksoutlined above by maintaining the temperature ofthe range of 1,250 to1,700" F. I prefer to preheat the feed to the reaction zone to atemperature in the range of 500 to 1,000 F., and this can suitably beaccomplished in most instances by arranging to transfer heat removed ina quench zone to the hydrocarbon feed.

In the practicey of my invention there is developed within the solidcarbonaceous material an incandescent zone.

This zone can vary in various installations from 1 inch to 16 feet ormorein height, the upper limit being determined by the weight ofmaterial which the burning zone will support. This limitation, ofcourse, does not apply where the'bed is lluidized.

vThe height of the incandescent zone can be controlled by varying theoxygen to hydrocarbon ratio and the rate `of ow of the material throughthe bed. Suitable control means for the height of the incandescent zoneare discussed below.

In the drawing, FIGURE 1 is a vertical cross section of a simplifiedapparatus suitable for practicing the process of my invention. FIGURE 2is a vertical cross section of an apparatus suitable for use in acontinuous process with continuous heat transfer from the quench zone tothe inlet or preheat zone. FIGURE .3 is a vertical cross section of areactor which permits utilizing heat removed in the quench zone byperiodically reversing the direction of flow, thereby reversing thefunctions of the preheat and quench zones.

Referring now to FIGURE 1, this apparatus comprises -inlet tube 10,reaction chamber 11, outlet tube 12, perforated support 13, heater 14,and thermocouple 15, and the perforated support 13 supports a bed 16 ofsolid carbonaceous material. In a specific embodiment used forexperimental purposes, inlet tube 10, reaction chamber 11, and outlettube 12 are all formed in a 17 mm. I.D. stainless steel tube.

In FIGURE 2 thereactor 20 comprises a preheat chamber 21, a reactionchamber 22, and a quench chamber 23. Transfer tube 24 extends from theportion of chamber 23 adjacent chamber 22 to the portion of chamber 21adjacent chamber 22. Transfer tube 25 extends from the portion ofchamber 21 removed from chamber 22 to Ithe portion of chamber 23 removedfrom chamber 22. .An inlet 26 is provided for solid carbonaceousmaterial which forms a bed 27 in chamber 22. Reactant inlet 28 andproduct removal line 29 are provided as shown. A rst perforated plate 30is provided at the lower end of charnber 21, a second perforated plate31 divides chamber 21 from `chamber 22, and a third perforated plate 32is provided at the lower end of chamber 23. A bed 33 is maintained inchamber 23 of inert particles such as ceramic, metal or Cermet Thelatter denotes a groupof materials made up of ceramic and metallicconstituents, usually processed by powdered metallurgy techniques. Theycomprise, for example, borides of nickel, copper, barium, manganese andchromium; carbides of titanium, tantalum, columbium, molybdenum,vanadium, chromium, zirconium, and boron; the nitrides of silicon,titanium, zirconium, hafnium, vanadium, scandium, iobium, tantalum,tungsten, thorium, and uranium; and the silicides of calcium, manganese,iron, copper, boron, magnesium, vanadium, and titanium in combinationWith such ceramic-like materials as iron and aluminum oxide, titaniumoxide, and the like.

Properties of these materials which may be used to an advantage,particularly when a uidized operation is contemplated, are:

(1) Low attrition losses;

(2) High density and rapid heat transfer permitting high iiow rates;

(3) High resistance to thermal shock; and

(4) A highly inert surface.

A similar bed 34 is maintained in chamber 21. To transfer heat fromchamber 23 to chamber 21, inert particles are transferred continuouslyfrom chamber 23 to chamber 21 through transfer tube 24 and particles aretransferred at the same rate from chamber 21 to chamber 23 ythrough 25.Flow through transfer tube 24 is by gravity, the rate being controlledby suitable means such as star valve 35. The particles, of course, mustbe lifted through tube 25 and this can be done, for example, by usingair lifting methods as by injecting air at 36. Air or otheroxygen-containing material may be introduced with a reactant throughinlet 28 or may be passed directly into chamber 22 through suitableinlets not shown. An incandescent zone 37 is maintained within bed 27.To control this zone, two light sensing elements such as phototubes 33yare positioned to see the area above land below the incandescentinterface. When both the reactant and air are introduced through inlet28, a ratio controller 40 can be used to control the relative rates offlow `of air through valve 41 Iand reactant through valve 42. Phototubes38 are connected to an amplifier which provides a signal to change thesetpoint of ratio controller 40 to change the ratio of air Ito reactantand thus control the height of the incandescent zone. The phototubeabove the interface is normally inactive but if the interface rises to apoint where this tube becomes illuminated, the ratio controller isactivated to provide a richer mixture. The lower tube is positioned sothat it normally sees the light. If the light intensity decreases belowa predetermined value, the reduction of the amplier response activatesratio controller 40 to provide a leaner mixture at inlet 28. Theconstruction and operation of `the various components of the controlsystem are gell known and, therefore, need not be described in detailere.

An important vari-able in the conve-rsion process of the presentinvention is the reaction time. For example, in the manufacture ofolens, reaction times in the range 0.001 to 2 seconds are utilized. Whenthe height of the incandescent Zone is established and the flow rate andfeed to oxidant ratio are constant the reaction time remains constant.Reasonable variation in the reaction time is permissible within adesired range. However, in general, the reaction time should beestablished in the lower range when operating in the upper range of thetemperature range and vice versa.

In FIGURE 3, chambers 50 and 51 are lled with refractory material and abed of carbonaceous material is maintained in chamber 52. Reactant andoxidant enter through lines 53 and 54, respectively, and are directed bythree-way valve 55 to inlet lines 56 and 57 alternately. When the flowis through line 56 the mixture enters chamber 50, valve 58 being closed,and flows from. there through reaction chamber 52 and through chamber 51and out to product recovery through valve 59. Suitable automatictemperature controllers, not shown, can be used if desired to operatevalves 5S, 58, and 59 and these automatic controllers can in turn beactuated by the temperatures in chambers 50 and 51. Periodically thedirection of flow Iis reversed by reversing the position of three-wayvalve 55, thus directing the flow through inlet 57 and removing theproduct through valve 58 to product recovery. It will be seen that thistype of operation permits heat removal in either chamber 50 or 51 to beutilized to preheat the mixture when the ow is reversed. Suitable meansfor controlling the inlet of solid carbonaceous material to chamber 52can be used such as star valve 60 and ashes can be removed throughconduit 61 by suitable means, such as a conveyor, not shown.

In the operation of the present invention it has been found that theott-gas remaining after recovery of the oleins produced contains arelatively high concentration of hydrogen, carbon monoxide, and methane,thus making it suitable for use as a commercial heating gas. Ethyleneand propylene can, therefore, be manufactured from propane, for example,in countries where the latter material must be imported and governmentrestrictions require an -account of heat content of materials enteringinto a process and practically full conversion of this heat content toenergy.

A hypersorption recovery system can be advantageously employed in theseparation of the olein product from the ott-gas. However, it is alsopossible to use more conventional fractionation systems if desired.

In one example of the invention, a 40 millimeter vertical Vycor tube 20inches long was packed with 5 inches of inert (non-catalytic) ceramicspheres. On this inert support was placed a bed of Wood charcoal 8inches deep. The charcoal was broken, classified, and only those piecesfalling in the particle size range of 1A; inch to 1A inch were utilized.Propane and air mixture liowing at the rate of 0.834 standard cubic feetper hour propane and 10.25 standard cubic feet per hour of air Wereadmitted to the bottom of the packed section and ignited. Under theseconditions, the bottom of the charcoal layer became red hot for a heightof one inch and stabilized. Samples of oli-gas were collectedrepresenting the stabilized reaction products. Table I gives theanalysis of the composite sample collected.

This analysis indicates that 28 percent of the propane was beingconverted to oleiins (ethylene-l-propylene) and that 68 percent of theCO and CO2 originated from the charcoal.

In a second run, the same tube was utilized as in the first run. Thecharcoal bed had been reduced in height to 6.5 inches. Propane at therate of 2.64 standard cubic feet per hour `and air at the rate of 30.2standard cubic feet per hour were charged to the bottom of the packedsection. The red hot zone in the charcoal bed stabilized at a height ofapproximately 3 inches. Analysis of the ofi-gas collected as a compositesample is given in Table II.

This analysis indicates that 29 percent of the propane was converted tooleins and that 52 percent of the CO and CO2 came from the combustion ofcharcoal.

These results were especially promising because no attempt had been madeto compensate for the gross heat losses from the reaction zone, asomewhat different arrangement of apparatus was utilized. FlGURE 1 showsthe details of the apparatus. A 17 millimeter I.D. stainless steel tubewas utilized for this run. A water saturated mixture of 70.8 percentpropane and 29.2 percent air at a rate of 206 standard cubic feet perhour per square foot was charged to the top of the tube. Near the centerof the tube, a stainless steel fritted disk approximately 1/s inch thicksupported a bed of crushed wood charcoal having a particle size in therange through a 1/s inch mesh and retained on a 'S2-mesh screen. Belowthe fritted disk a thin-Walled stainless tubing containing thermocoupleleads traversed the lower, unpacked, reactor tube, pierced the fritteddisk and terminated-within the charcoal bed approximately 3/4 inch abovethe top of the fritted disk. The thermocouple junction was welded to theclosed end of the stainless tubing and was packed with swaged magnesia.A resistance heater was placed around the section containing thecharcoal for a distance 0f one and one-fourth inches above the uppersurface of the fritted disk. The reaction zone was preheated to atemperature of approximately 1,400 F. as measured by the thermocouple.The gas was ignited and after a brief period or uctuation thetemperature, as measured by the thermocouple, lined out at 1,3 S51-5 Fwhich was probably Within the limit of accuracy in measuring thetemperature. A sample taken after conditions had stabilized indicatedthe following ott-gas composition.

Table Ill Constituent Mol Constituent Mol percent percent CH4 12. 1Ethylene... 10. 5 Ethane 0.9 Propylene.. 7 3 Propane 26. 8 Butylenes 0.3

These data indicate that approximately 28 percent of the propane chargedis converted to oletins, but more than 1A of the propane will beavailable for recycle after recovery of the olefins which indicates thatgreater ultimate yields will be experienced. The analysis indicates thatthe olf-gas would have an available heat content of approximately 376Btu. per cubic foot. However, if oxygen was substituted for air a valueapproaching 837 Btu. per cubic foot could be attained. Values betweenthese extremes could be attained by operating with oxygen-enriched air.

When it is desired to use a iiuidized bed of solid carbonaceous materialfor the practice of this invention, control of the reaction time isaccomplished through control of the depth of the tiuidized bed since,through the fluidizing action, the bed may be incandescent throughoutits depth. Control of the uidized bed is accomplished by controlling oneor more of (l) the amount of solid carbonaceous material present in thebed at a given time and (2) the amount and rate of flow of fluidizinggas in the bed. The amount of material in the bed is, of course,controlled by regulating the iiow of solid carbonaceous material intoand out of the reaction zone. The fluidizing action Within the zone iscontrolled by regulating the flow of reactant and/or oxidizing gas,either of which may be controlled in conjunction with or independent ofthe other. Thus, use of a fludized bed permits a Very iiexible operationin that control of the reaction time can be obtained with some degree ofindependence of the other reaction vairables. It will be recognized thatthose skilled in the art of tluidized bed reactions can eiect suchcontrols given the teaching of the present disclosure.

Reasonable rvariation and modification are possible within the scope ofthe foregoing disclosure, the drawing, and the appended claims to theinvention, the essence of which is a hydrocarbon conversion process inwhich at least a portion of the endothermic heat of the reaction issupplied by oxidizing a solid carbonaceous material in the presence ofthe hydrocarbon being converted; the control of the reaction time isobtained by controlling the height of an incandescent zone of the solidcarbonaceous material and the rate of tioW of hydrocarbon through thereaction zone, a uidized bed is provided in which the height of theincandescent zone is controlled by controlling the depth of the bed; andapparatus for performing endothermic reactions.

I claim: 1. A hydrocarbon conversion process, comprising the steps ofpassing a hydrocarbon through a reaction zone in contact with a bed ofsolid carbonaceous material contained therein, under conditions toeffect an endothermic conversion of said hydrocarbon; igniting said bed;simultaneously passing a `sutiicient amount of an oxidizing agent withsaid hydrocarbon through said bed to oxidize exothermically a sutiicientquantity of said solid carbonaceous material to provide and maintain anincandescent zone Within said bed, to maintain desired operatingtemperature continuously, and to supply a major portion of 'the heatrequired for the endothermic conversion of said hydrocarbon; and

controlling the reaction by controlling the height of said incandescentzone and the rate of flow of said hydrocarbon through said zone.

(l L) 2. A hydrocarbon conversion process, comprising the steps of:

passing a hydrocarbon through a reaction zone in contact with a bed ofsolid carbonaceous material contained therein, under conditions toeffect an endothermic conversion of said hydrocarbon;

igniting said bed;

simultaneously passing a sufficient amount of an oxidizing agent withsaid hydrocarbon through said bed to oxidize exothermically a suicientquantity of said solid carbonaceous material to provide and maintain anincandescent zone Within said bed, to maintain desired operati-ngtemperature continuously, and to supply a .major portion of the heatrequired for the endothermic conversion of said hydrocarbon; and

controlling the reaction by controlling the height of said incandescentzone by sensing the height from the upper level of said incandescentzone and reducing the ratio of oxidizing agent to hydrocarbon when theheight exceeds the desired height, and increasing the ratio of oxidantto hydrocarbon when the height falls below the desired height, Whilemaintaining the rate of flow of said hydrocarbon through said zone at apredetermined Value.

References Cited in the file of this patent UNITED STATES PATENTS1,972,898 Odell Sept. 1l, 1934 2,684,390 Bills July 30, 1954 2,752,407Cahn June 26, 1956 2,767,233 Mullen et al, Oct. 16, 1956 2,790,838Schrader Apr. 30, 1957 2,824,148 Keulemans et al Feb. 18, 1958 2,870,087Gilmore Ian. 20, 1959

1. A HYDROCARBON CONVERSION PROCESS, COMPRISING THE STEPS OF: PASSING AHYDROCARBON THROUGH A REACTION ZONE IN CONTACT WITH A BED OF SOLIDCARBONZCEOUS MATERIAL CONTAINED THEREIN, UNDER CONDITIONS TO EFFECT ANENDOTHERMIC CONVERSION OF SAID HYDROCARBON; IGNITING SAID BED;SIMULTANEOUSLY PASSING A SUFFICIENT AMOUNT OF AN OXIDIZING AGENT WITHSAID HYDROCARBON THROUGH SAID BED TO OXIDIZE EXOTHERMICALLY A SUFFICIENTQUANTITY OF SAID SOLID CARBONACEOUS MATERIAL TO PROVIDE AND MAINTAIN ANINCANDESCENT ZONE WITHIN SAID BED, TO MAINTAIN DESIRED OPERATINGTEMPERATURE CONTINUOUSLY, AND TO SUPPLY A MAJOR PORTION OF THE HEATREQUIRED FOR THE ENDOTHERMIC CONVERSION OF SAID HYDROCARBON; ANDCONTROLLING THE REACTON BY CONTROLLING THE HEIGHT OF SAID INCANDESCENTZONE AND THE RATE OF FLOW OF SAID HYDROCARBON THROUGH SAID ZONE.